Edit Step 4 ¶
You will probably want three strips of heatshrink. They will need to fit over each other shrunk in place so likely need to be different sizes.
Cut the smallest diameter sleeve to 2cm long. Once shrunk into place the white plastic outer will need to fit over this. You might wish to check that this will work, as otherwise you will need to enlarge the hole in the housing (now, not later!).
Cut the others a little longer each e.g. 2.5cm and 3cm.
Slide the largest diameter heatshrink over the cable.
Slide on the next largest size
Push the remains of the strain relief out of the white plastic outer housing. Now slide on the plastic outer part of the magsafe connector. Make sure that you get it the right way round!
Finally, slide on the smallest piece of heatshrink.
Edit Step 5 ¶
Peel back the braid
Tease out the fibres that are contained within the braid and then cut them off as close to the cable as possible.
Split the braid in to two equal parts. Twist each part separately to make two neat wires.
Strip back 3mm of insulation from the inner core. Twist the core by hand and then tin the end.
Edit Step 6 ¶
Solder the core on to the opposite side to the chip (in the opposite corner).
Cut two pieces of the smallest heatshrink - roughly 4mm long.
Slide on to the braid leaving roughly 3mm of braid free at the end where it joins the cable.
Shrink in to place. If your heat gun is a bit powerful, use the soldering iron to supply the heat.
Cut off the braids leaving about 3mm free beyond the heatshrink.
Solder the first braid on to the chip side in the opposite corner to the chip.
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